Change of deformation mode caused by aging of Ti-14 mass%Mo alloy single crystals and embrittlement mechanism due to the ω-phase

Yosito Takemoto, Moritaka Hida, Eiiti Sukedai, Akira Sakakibara

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Abstract

A change of deformation modes in lattice instable Ti-14 mass%Mo alloy single crystals upon aging treatments at 623 K was investigated in the tensile test up to rupture. The tensile direction of these specimens was [116]B. The main deformation modes of as-quenched specimen (AQ) were {332} 〈113〉 and {112} 〈111〉 mechanical twins. Their Schmid factors (SF) were 0.321 and 0.156 in {332} 〈113〉 twins and 0.447 in {112} 〈111〉 twins. A specimen aged for a short time of nearly 250 s (AG (S)) showed a kind of transitional state of deformation mode which involved {332} 〈113〉 twins, {112} 〈111〉 twins and {112} 〈111〉 slips. In this state AG(S) had been already poor in ductility. A specimen long aged for 1 × 105 s (AG(L)) showed a remarkable brittle fracture caused by the aged ω phase, but it was not the {001} cleavage fracture. The fracture surface had a chevron pattern induced by the operation of some {112} slip systems in the initial stage. Large grown aged ω variants caused the B matrix to remarkably increase the stress level for deformation and induced locally an Ω→B inverse transformation. Local softening which occurred with the inverse transformation led to an extreme stress concentration and then to crack. In this way AG(L) apparently showed notable embrittlement.

Original languageEnglish
Pages (from-to)1004-1012
Number of pages9
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume53
Issue number10
DOIs
Publication statusPublished - Jan 1 1989

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ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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